Electromagnetic relay



Jan. 6 1959 G. MAKowsKl ELECTROMAGNETIC RELAY Filed April 26. 1956United States Patent ELECTROMAGNETIC RELAY Giinther Makowski, Munich,Germany, assigner to Siemens & Halske Aktiengesellschaft, Berlin andMunich, Germany, a corporation of Germany Application April 26, 1956,Serial No. 580,883

lClaims priority, application Germany May 10, 1955 4 Claims. (Cl.317-187) This invention is concerned with an electromagnetic relaycomprising means for locking its armature in operated position.

Various interlocking relays of the a-bove-noted general character havebecome known. Some of these structures are provided with special linkcontrolled locking niembers or with several armatures, one armatureacting as a locking means for the other armature; other structuresprovide permanent magnets in the iron path or omit the usual residualstud on the armature so as to eiiect retention thereof in operatedposition. The two first mentioned structures require relatively greatexpenditure for auxiliary parts and in some cases greater operatingenergy; in the two last-mentioned embodiments, the actuation isadversely affected by jarring and by contamination of the core andarmature surfaces.

The object of the invention is to provide a reliably operatinginterlocking relay requiring small expenditure so far as auxiliary partsare concerned and which does not require higher operating energy than arelay of the customary normal type. This object is realized by theprovision of a non-magnetic hooklike latch or locking member which ispivotally disposed at the free armature end facing the air gap, suchlatch member carrying a permanent magnet.

Details of the invention will appear from the description of anembodiment which is rendered below with reference to the accompanyingdrawing showing in schematic manner only relay parts required for anunderstanding thereof. In the drawing,

Fig. l shows the new structure partially in section and with the partsin normal position; and

Fig. 2 shows the structure in locked position.

At the free end of an armature 1 is disposed a hooklike latch member 3which is pivoted at 2. The latch 3 carries a permanent magnet 4. Thearea of pivotal motion of the latch 3 is in one direction limited by astop 5 and in the other direction by the end 6 of the armature. It ishowever possible to form the means which hold the permanent magnet onthe latch 3 so that they define the limit positions thereof.

In the normal position of the corresponding relay, with the armaturerestored, the permanent magnet 4 will be within the stray magnetic eldof the electromagnet of which only the core 7 is shown in the drawing.Upon energization of the relay, the armature 1 will be attracted to thecore 7 until the residual member 8 is in engagement therewith. The straymagnetic iield increasingly aiects the permanent magnet 4 on the latch3, during the attraction of the armature, and such magnet is accordinglylikewise attracted by the core 7 and rotates the latch 3counterclockwise from the position shown in Fig. l to the interlockingposition shown in Fig. 2, the angular free end 9 of the latch engagingover the end of the core 7 as shown in Fig. 2. Upon interruption of theenergizing current for the corresponding relay, the

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armature 1 will remain locked in operated position due to the interlockbetween the latch extension 9 with the core '7. Any small idlingdisplacement of the armature toward normal-or released position thereof,incident to interruption of the energizing current, will merely be by anamount just suricient to allow the latch extension 9 to engage the core7; such fractional idling displacement will not atect the relaycontacts.

The armature release is effected by exciting the correspending relaywinding in a sense opposite to the operatively eiective energizationthereof, thereby polarizing the core 7 likewise in opposite sense. Thearmature 1 is now attracted `by the small amount of its fractionalrestoring motion responsive to interruption of the energizing current,and inasmuch as the permanent magnet 4 is now of the same polarity :asthe core v7, it will be repelled, causing clockwise rotation of thelatch 3 to retract the extension 9 from interlocking engagement with thecore 7. The energy required for the excitation of the relay winding inopposite sense to its operatively eiective excitation, to eifectrestoration of the armature, is lower than the energy required for theattraction thereof.

Changes may be made within the scope and spirit of the appended claims.

I claim:

l. In an electromagnetic relay having a core and a movable armature thefree end of which is in normal position spaced by an air gap from thefree end of the core, a device for holding the armature in attractedposition after attraction thereof responsive to energization of saidcore, said device comprising a non-magnetic latch member rotatablymounted at the free end of said armature, and a permanent magnet carriedby said latch member and forming a unit therewith, the polarization ofsaid permanent magnet being in a sense opposite to the polarization ofsaid core resulting in the energization thereof to effect attraction ofsaid armature, so as to cause incident to the attraction of saidarmature attraction of said permanent magnet and consequently rotationof said latch member to place such latch member in interlockingengagement with said core.

2. A structure and cooperation of parts according to claim 1, comprisingstop means for defining the limits of rotary motion of said latchmember.

3. A structure and cooperation of parts according to claim 1, comprisinga residual member disposed between said armature and said core, thewidth of said air gap exceeding in holding position of said armature thethickness of said residual member.

4. A structure and coperation of parts according to claim l, whereinrelease of said armature is effected by energization of said core in asense opposite to the sense of energization thereof to elect attractionof said armaure, for the purpose of causing polarization of said corecorresponding to the polarization of said permanent magnet, whereby saidpermanent magnet is repelled from said core so as to rotate said latchmember to normal, thereby breaking the interlocking engagement of suchlatch member with said core and permitting release of said armature.

References Cited in the file of this patent UNITED STATES PATENTS2,343,199 Mayer Feb. 29, 1944 FOREIGN PATENTS 2,930 Great Britain Feb.6. 1901

